Hilary DuffHilary Duff is less than impressed that her ex-boyfriend Joel Madden is already seeing Nicole Richie, just weeks after he and Hilary went their separate ways.

Hilary and the Good Charlotte frontman dated for two years before splitting last month.

A source told Us Weekly: “[Hilary] can’t believe he’s dating Nicole and thinks she’s a skank.”

The source added that Hilary was surprised when she heard Nicole was driving back from Joel’s when she was arrested for driving under the influence, having smoked marijuana and taken Vicodin: “she asked if Nicole had been coming from Joel’s. … She kept saying she never knew Joel at all.”

Hilary has had a long running feud with Lindsay Lohan after Aaron Carter left Lindsay for Hilary in 2002.